1. Field of Art
The present invention relates to agricultural harvesters, such as combine harvesters, having a storage tank for harvested crop material. More particularly, it relates to retractable extension means for temporarily extending the volume of said storage tank.
2. Description of Prior Art
Commonly, combine harvesters are provided with large capacity grain tanks for temporarily storing the harvested and cleaned grain before it is discharged, at appropriate intervals, into attendant vehicles or any other suitable receptacle. As the harvesting capacity of modern combines increases, there is a need for larger grain tanks. However, the possibilities for increasing the grain tank volume are not unlimited. Road transport regulations set limits to the maximum width and height of the vehicle. Furthermore, the space requirements for the crop processing apparatus below the grain tank tends to increase, thereby raising the lowest point available for grain storage.
In order to cope with this problem, the grain tank can be provided with a collapsible top portion, which is put down in a lower, inoperative position for road transport, and which is raised to a higher, operative position for harvesting operations. Such collapsible grain tank extensions are described in GB-A-2 296 175, U.S. Pat. No. 4,466,549 and EP-A-0 819 371.
It is required that the extended top portion be sturdy to hold large masses of grain, which are subject to forces in various directions resulting from the movement of the combine over the field. Still the grain tank extensions should be easy to lift and lower, to adapt quickly to alternating road and field conditions.
According to the present invention, there is provided an agricultural harvesting machine, having a wheeled main frame, a means for collecting and processing crop material from a field, a storage tank affixed to said main frame for storing therein said processed crop material; and an extension means associated with said storage tank. The extension means having a first pair of mutually opposed panels and a second pair of mutually opposed panels. The first and second pair of panels being movable between a lower, inoperative position and a higher, operative position in which said panels substantially increase the effective volume of said storage tank, the movement of the second pair being controllable by the movement of the first pair.
The panels of the first and second pairs are provided with locking means for keeping all panels in their operative position, said locking means being disposed to become engaged and to secure the panels in their operative position when said first pair of panels moves the second pair of panels to their operative position.
This interlocking feature of the grain tank panels provides for a sturdy tank extension, which is easily lowered or raised. Members, such as rollers, may be provided on the panels of the first pair for engaging the inner surface of the panels of the second pair during raising or lowering action. Advantageously, the panels of the second pair may have means for keeping the rollers against their inner surface, thereby preventing unwanted outward movement of these panels. This may be realised by a curved profile which is arranged along the path of the rollers.
To permit simultaneous erection of the panels of the first pair, they may be interconnected by transmission means, for example a rotatable transmission shaft which is connected by rods to these panels. The rods may be connected to the shaft at points having a different distance to the rotation axis, thereby permitting loading of the one panel before the other panel is loaded.
The processed crop is discharged into the tank by an elevator which advantageously has a movable portion which can lowered below the top level of the closed tank. A rod connecting the movable portion to one of the panels provides for automatically bringing the elevator into its active position when the tank extension is raised.
When the machine is provided with a controller like a microprocessor, for controlling the actuator which moves the panels between their operative and inoperative positions, and a grain tank level indicator, the controller can be used to prevent retraction of the actuator to close the extensions in case the indicator senses a grain tank level above a predetermined level. In this manner inadvertent closing of a filled grain tank and subsequent damage to the actuator and/or panels is precluded.